Various door operating mechanisms have been designed to operate with various styles of doors. Frequently each type of operator is applied to a specific style of door. The most common types of doors which are mechanically operated can be separated into two general categories, i.e. sliding/rolling doors and hinged/pivoting doors. The pesent invention can be applied most readily to the hinged/pivoting type of door.
A hinged or pivoting type of door structure can be defined as a door structure which incorporates a large rigid panel suitably mounted or attached to a frame so as to pivot about an axis which is normally parallel to the longest edge of the panel. Frequently the door is supported by a plurality of hinges having one end fixedly secured to the edge of the door and the other end being fixedly secured to the door frame or doorjamb. The door then pivots about these hinges into open and closed positions. Frequently the pivotal motion of the door is about a vertical axis but this need not be the case and the door may be mounted for pivoting about a horizontal axis.
Another common type of hinged door is the folding door in which one or more panels are hinged together and attached to a panel which is hinged to the doorjamb. Both of these styles are very common in residential areas and are also very useful in industrial commercial applications.
Doors utilized in industrial and commercial applications may be very large in size, occasionally exceeding twenty feet in height and thirty in width. The present invention is especially constructed and arranged to easily open and close large commercial and industrial doors which satisfy the industrial and commercial standards therefor. However, the present invention can also be applied to residential use.
Currently there are many door operators designed for industrial and commercial use. One style of operator has a rotary actuator mounted onto the hinge. This style of operator is concealed above or below the door and is sometimes mounted along the height of the door where space permits. While this version of door operator is effective on relatively small doors, a drawback to this type of operator is that an extreme amount of torque is required to rotate the door if there is any load on the door due to large size, wind, etc. This in turn, requires relatively large hinges and hinge pins to evenly distribute loading, and also requires a very heavy-duty operator.
To overcome this problem, operators have been designed to fit in the space between the top of the door opening and the ceiling area. A typical design for this style of door operator might consist of two gear boxes driven by two separate motors or one motor on a common shaft. The output of each gear box is then conveyed to the door through a series of linkages or lever arms. The problem associated with this type of operator is that it requires considerable headroom which is sometimes not available. Another drawback is that the action of the mechanism is very hard to visualize and difficult to optimize prior to installation without individually laying out each size of door opening to verify that the mechanism will perform satisfactorily without hitting any part of itself or the door surroundings as it operates. A further drawback of this style of door operator is that it operates on the top edge of the door and can cause the door to twist as it opens and closes. This condition becomes worse as the loading and size of the door increase or if the door must be stopped midway in its operation.
Since some installations do not have sufficient headroom to permit the above described operator to be utilized, a similar style door operator is often mounted onto the top edge of the door instead of above the door. Such a door operator causes twisting of the door due to its location. It also requires additional side room when the door is open and places additional weight on the door subjecting the door and its supporting hinges to additional stress. Another drawback to top mounted door operatives is that maintenance is difficult to perform due to the high location.
Another approach has been to mount a door operator on the wall along the side of the door. This allows the opening and closing action of the operator to be transferred to the middle portion of the door which more effectively distributes loads thereby preventing twisting of the door. However, some doors can not be operated in this fashion due to insufficient side room to install the door operator.
Yet another approach has been to use an air cylinder to operate a spring arm mounted above the door. Such a door operator requires careful adjustment of geometry and action of the mechanism to provide satisfactory operation. The operation of the mechanism is also somewhat depenedent upon the loading on the door and has many of the problems attributed to the other styles of top mounted operators.
Some door operators have utilized an electrically operated hydraulic cylinder which is attached at one end thereof to a bracket in the middle of the door and attached at the other end thereof to a bracket located inside the doorjamb. The door operator mounted in this position projects out into the doorway when the door is open and is therefore frequently in the way of objects passing through the door opening.
The present invention overcomes many of these problems in the prior art by use of a linkage mechanism for converting linear force into a door opening and closing force.